Research

20 pages, 10238 KiB

Open AccessArticle

Estimation of Sound Transmission Loss in Nanofiber Nonwoven Fabrics: Comparison of Conventional Models and the Simplified Limp Frame Model

by Shuichi Sakamoto, Tsukasa Hasegawa and Koki Ikeda

Nanomaterials 2023, 13(22), 2947; https://doi.org/10.3390/nano13222947 - 14 Nov 2023

Viewed by 710

Abstract

Although the sound absorption coefficients of conventional and nanofiber nonwoven fabrics (NF-NWFs) have been the subject of many previous studies, few studies have considered the estimation of transmission loss. Reported herein is an experimental and theoretical study into estimating the transmission loss of [...] Read more.

Although the sound absorption coefficients of conventional and nanofiber nonwoven fabrics (NF-NWFs) have been the subject of many previous studies, few studies have considered the estimation of transmission loss. Reported herein is an experimental and theoretical study into estimating the transmission loss of NF-NWFs using four estimation models, i.e., the Rayleigh, Miki, and Komatsu models, and the simplified limp frame model (SLFM), with the model results compared against the experimental data. The transmission loss of the NF-NWF was determined from the propagation constant, and characteristic impedance was calculated using the estimation model and the transfer matrix method. The validity of each estimation method was examined by comparing its estimated values with the experimental values measured using a four-microphone impedance measurement tube. The proposed SLFM is more suitable for estimating the transmission loss of NF-NWFs than the conventional Rayleigh, Miki, and Komatsu models. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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13 pages, 1572 KiB

Open AccessArticle

First Principle Study on the Effect of Strain on the Electronic Structure and Carrier Mobility of the Janus MoSTe and WSTe Monolayers

by Jawad El Hamdaoui, Laura M. Pérez, Miguel Ojeda-Martínez, Nassima El Ouarie, Pablo Díaz, David Laroze and El Mustapha Feddi

Nanomaterials 2023, 13(18), 2535; https://doi.org/10.3390/nano13182535 - 11 Sep 2023

Viewed by 990

Abstract

Using first-principle calculations, we investigate the impact of strain on the electronic structures and effective masses of Janus WSTe and MoSTe monolayers. The calculations were performed using the QUANTUM-ESPRESSO package, employing the PBE and HSE06 functionals. Our results demonstrate that strain fundamentally changes [...] Read more.

Using first-principle calculations, we investigate the impact of strain on the electronic structures and effective masses of Janus WSTe and MoSTe monolayers. The calculations were performed using the QUANTUM-ESPRESSO package, employing the PBE and HSE06 functionals. Our results demonstrate that strain fundamentally changes the electronic structures of the Janus WSTe and MoSTe monolayers. We observe that deformation causes a shift in the maxima and minima of the valence and conduction bands, respectively. We find that the effective electrons and hole masses of MoSTe and WSTe can be changed by deformation. In addition, the strain’s effect on carrier mobility is also investigated in this work via the deformation potential theory. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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9 pages, 4031 KiB

Open AccessArticle

Coexistent VO₂ (M) and VO₂ (B) Polymorphous Thin Films with Multiphase-Driven Insulator–Metal Transition

by Mengxia Qiu, Wanli Yang, Peiran Xu, Tiantian Huang, Xin Chen and Ning Dai

Nanomaterials 2023, 13(9), 1514; https://doi.org/10.3390/nano13091514 - 28 Apr 2023

Cited by 2 | Viewed by 1028

Abstract

Reversible insulator–metal transition (IMT) and structure phase change in vanadium dioxide (VO₂) remain vital and challenging with complex polymorphs. It is always essential to understand the polymorphs that coexist in desired VO₂ materials and their IMT behaviors. Different electrical properties [...] Read more.

Reversible insulator–metal transition (IMT) and structure phase change in vanadium dioxide (VO₂) remain vital and challenging with complex polymorphs. It is always essential to understand the polymorphs that coexist in desired VO₂ materials and their IMT behaviors. Different electrical properties and lattice alignments in VO₂ (M) and VO₂ (B) phases have enabled the creation of versatile functional devices. Here, we present polymorphous VO₂ thin films with coexistent VO₂ (M) and VO₂ (B) phases and phase-dependent IMT behaviors. The presence of VO₂ (B) phases may induce lattice distortions in VO₂ (M). The plane spacing of (011)_M in the VO₂ (M) phase becomes widened, and the V-V and V-O vibrations shift when more VO₂ (B) phase exists in the VO₂ (M) matrix. Significantly, the coexisting VO₂ (B) phases promote the IMT temperature of the polymorphous VO₂ thin films. We expect that such coexistent polymorphs and IMT variations would help us to understand the microstructures and IMT in the desired VO₂ materials and contribute to advanced electronic transistors and optoelectronic devices. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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9 pages, 959 KiB

Open AccessArticle

Ga-In Alloy Segregation within a Porous Glass as Studied by SANS

by Andrei V. Uskov, Elena V. Charnaya, Aleksandr I. Kuklin, Min Kai Lee, Lieh-Jeng Chang, Yurii A. Kumzerov and Aleksandr V. Fokin

Nanomaterials 2023, 13(8), 1357; https://doi.org/10.3390/nano13081357 - 13 Apr 2023

Viewed by 854

Abstract

Nanolattices can play the role of templates for metals and metallic alloys to produce functional nanocomposites with particular properties affected by nanoconfinement. To imitate the impact of nanoconfinement on the structure of solid eutectic alloys, we filled porous silica glasses with the Ga-In [...] Read more.

Nanolattices can play the role of templates for metals and metallic alloys to produce functional nanocomposites with particular properties affected by nanoconfinement. To imitate the impact of nanoconfinement on the structure of solid eutectic alloys, we filled porous silica glasses with the Ga-In alloy, which is widely used in applications. Small-angle neutron scattering was observed for two nanocomposites, which comprised alloys of close compositions. The results obtained were treated using different approaches: the common Guinier and extended Guinier models, the recently suggested computer simulation method based on the initial formulae for neutron scattering, and ordinary estimates of the scattering hump positions. All of the approaches predicted a similar structure of the confined eutectic alloy. The formation of ellipsoid-like indium-rich segregates was demonstrated. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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9 pages, 2992 KiB

Open AccessArticle

Multi-Parametric Birefringence Control in Ultrashort-Pulse Laser-Inscribed Nanolattices in Fluorite

by Sergey Kudryashov, Alexey Rupasov, Mikhail Smayev, Pavel Danilov, Evgeny Kuzmin, Irina Mushkarina, Alexey Gorevoy, Anna Bogatskaya and Alexander Zolot’ko

Nanomaterials 2023, 13(6), 1133; https://doi.org/10.3390/nano13061133 - 22 Mar 2023

Viewed by 1268

Abstract

An ultrashort-pulse laser inscription of embedded birefringent microelements was performed inside bulk fluorite in pre-filamentation (geometrical focusing) and filamentation regimes as a function of laser wavelength, pulsewidth and energy. The resulting elements composed of anisotropic nanolattices were characterized by retardance (Ret) [...] Read more.

An ultrashort-pulse laser inscription of embedded birefringent microelements was performed inside bulk fluorite in pre-filamentation (geometrical focusing) and filamentation regimes as a function of laser wavelength, pulsewidth and energy. The resulting elements composed of anisotropic nanolattices were characterized by retardance (Ret) and thickness (T) quantities, using polarimetric and 3D-scanning confocal photoluminescence microscopy, respectively. Both parameters exhibit a monotonous increase versus pulse energy, going over a maximum at 1-ps pulsewidth at 515 nm, but decrease versus laser pulsewidth at 1030 nm. The resulting refractive-index difference (RID) Δn = Ret/T ~ 1 × 10⁻³ remains almost constant versus pulse energy and slightly decreases at a higher pulsewidth, generally being higher at 515 nm. The birefringent microelements were visualized using scanning electron microscopy and chemically characterized using energy-dispersion X-ray spectroscopy, indicating the increase of calcium and the contrary decrease of fluorine inside them due to the non-ablative inscription character. Dynamic far-field optical diffraction of the inscribing ultrashort laser pulses also demonstrated the accumulative inscription character, depending on the pulse energy and the laser exposure. Our findings revealed the underlying optical and material inscription processes and demonstrated the robust longitudinal homogeneity of the inscribed birefringent microstructures and the facile scalability of their thickness-dependent retardance. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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14 pages, 2056 KiB

Open AccessArticle

Experimental Study of As-Cast and Heat-Treated Single-Crystal Ni-Based Superalloy Interface Using TEM

by Runjun He, Miao Li, Xiao Han, Wei Feng, Hongye Zhang, Huimin Xie and Zhanwei Liu

Nanomaterials 2023, 13(3), 608; https://doi.org/10.3390/nano13030608 - 02 Feb 2023

Cited by 1 | Viewed by 1260

Abstract

The interface plays an important role in determining strength and toughness in multiphase systems and the accurate measurement of the interface structure in single crystal (SX) Ni-based superalloy is also essential. In this work, the γ and γ′ lattice constant, γ/γ′ interface width [...] Read more.

The interface plays an important role in determining strength and toughness in multiphase systems and the accurate measurement of the interface structure in single crystal (SX) Ni-based superalloy is also essential. In this work, the γ and γ′ lattice constant, γ/γ′ interface width at dendritic and interdendritic region of casting and solution treatment SX Ni-based superalloy is measured. Various advanced equipment is used to characterize γ/γ′ interface nanostructure. A typical correlation between interface width and γ/γ′ misfit is also summarized. The interface width in the dendritic region of the as-cast sample is larger than that in the interdendritic region. The misfit in the dendritic region is larger than that in the interdendritic region, which has a trend of negative development. There is a common law of the as-cast interdendritic and dendrite interface sample, where the absolute value of the misfit between the two phases is increasing with the phase interface broadening. The comparison of the as-cast and heat-treated interdendritic sample shows that after heat treatment, the phase interface width increases, the misfit decreases, the lattice constant of γ phase increases, and the lattice constant of the γ′ phase decreases. By comparing the as-cast and heat treated dendrites, the absolute value of the misfit of the as-cast dendrite sample is significantly smaller than that of the heat-treated sample, and the misfit increases with the interface broadening. The comparison between interdendritic and dendritic heat-treated samples shows that the absolute value of the misfit between the two phases is smaller than that of the dendritic as-cast samples, and the absolute value of the misfit also increases with the phase interface broadening. In conclusion, property heat treatment can significantly increase the lattice constants of the γ and γ’ phases, reduce the lattice mismatch at the interface of the two phases, and improve the high temperature stability of the alloy. A better understanding of the microstructure of Ni-based single crystal superalloys will provide guidance for the subsequent design of more advanced nickel-based single-crystal superalloys. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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8 pages, 2702 KiB

Open AccessArticle

Magnetic Studies of Superconductivity in the Ga-Sn Alloy Regular Nanostructures

by Marina V. Likholetova, Elena V. Charnaya, Evgenii V. Shevchenko, Min Kai Lee, Lieh-Jeng Chang, Yurii A. Kumzerov and Aleksandr V. Fokin

Nanomaterials 2023, 13(2), 280; https://doi.org/10.3390/nano13020280 - 09 Jan 2023

Cited by 1 | Viewed by 1005

Abstract

For applications of nanolattices in low-temperature nanoelectronics, the inter-unit space can be filled with superconducting metallic alloys. However, superconductivity under nanoconfinement is expected to be strongly affected by size-effects and other factors. We studied the magnetic properties and structure of the Ga-Sn eutectic [...] Read more.

For applications of nanolattices in low-temperature nanoelectronics, the inter-unit space can be filled with superconducting metallic alloys. However, superconductivity under nanoconfinement is expected to be strongly affected by size-effects and other factors. We studied the magnetic properties and structure of the Ga-Sn eutectic alloy within regular nanopores of an opal template, to understand the specifics of the alloy superconductivity. Two superconducting transitions were observed, in contrast to the bulk alloy. The transitions were ascribed to the segregates with the structures of tetragonal tin and a particular gallium polymorph. The superconducting-phase diagram was constructed, which demonstrated crossovers from the positive- to the common negative-curvature of the upper critical-field lines. Hysteresis was found between the susceptibilities obtained at cooling and warming in the applied magnetic field. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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20 pages, 26617 KiB

Open AccessArticle

Experimental Study of the Thermally Grown Oxide and Interface of Thermal Barrier Coatings Using TEM In-Situ Heating

by Hongye Zhang, Runlai Peng, Jiaye Zhao, Chao Fan, Wei Feng and Zhanwei Liu

Nanomaterials 2022, 12(22), 4020; https://doi.org/10.3390/nano12224020 - 16 Nov 2022

Cited by 1 | Viewed by 1245

Abstract

Thermal barrier coating (TBC) materials play important roles in gas turbine engines to protect the Ni-based superalloys from high-temperature airflow damage. In this work, the nano-mechanism of TBC failure is analyzed. A scanning transmission electron microscopy-energy dispersive spectrometer (STEM-EDS)-based analysis method was used [...] Read more.

Thermal barrier coating (TBC) materials play important roles in gas turbine engines to protect the Ni-based superalloys from high-temperature airflow damage. In this work, the nano-mechanism of TBC failure is analyzed. A scanning transmission electron microscopy-energy dispersive spectrometer (STEM-EDS)-based analysis method was used to study the influence of element migration on the deformation behavior of the bond–coat (BC) layer during heating. The content of elements in the same region varied greatly at different temperatures, which could prove the contribution of element migration to the deformation of the BC layer. TEM in-situ heating experiments were designed and carried out to study the deformation behavior near the ceramic topcoat (TC)/thermally grown oxide (TGO) and the TGO/BC interface. The TC/TGO interface was deformed violently during heating, and obvious deformation occurred at 100 °C, while the TGO/BC interface was relatively stable. A subset geometric phase analysis method was used for full field-strain measurement. The strain value near the TGO/BC interface was relatively small and did not change significantly at lower temperatures. The TC/TGO interface is more unstable and easier to deform than the TGO/BC interface. The stress and strain evolution in the internal region of TGO at high temperatures was quantitatively analyzed. The TGO layer has a tensile stress of GPa magnitude along the interface direction at the peak position, and the shear stress is small. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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9 pages, 2183 KiB

Open AccessArticle

A Study of Magnetic Properties in a 2D Ferromagnetic Nanolattice through Computer Simulation

by Sergey V. Belim and Igor V. Bychkov

Nanomaterials 2022, 12(20), 3705; https://doi.org/10.3390/nano12203705 - 21 Oct 2022

Cited by 1 | Viewed by 1205

Abstract

This article investigated the magnetic properties of a 2D nanolattice through computer modeling. A square antidote nanolattice in thin films was considered. For our computer simulation, we used the Heisenberg model. Ferromagnetic phase transition was studied for lattices with pores of various sizes. [...] Read more.

This article investigated the magnetic properties of a 2D nanolattice through computer modeling. A square antidote nanolattice in thin films was considered. For our computer simulation, we used the Heisenberg model. Ferromagnetic phase transition was studied for lattices with pores of various sizes. We determined the Curie temperature based on the finite-dimensional scaling theory. Using Wolf’s algorithm, we simulated the behavior of the system. The dependence of the phase transition temperature on the density of spins was found to be power. Using Metropolis’ algorithm, we calculated a hysteresis loop for an antidote lattice film. The hysteresis loop narrowed as the pore sizes increased. The dependence of coercive force on the size of the nanolattice obeyed the logarithmic law. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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10 pages, 2379 KiB

Open AccessArticle

Optically-Induced Symmetry Switching in a Reconfigurable Kagome Photonic Lattice: From Flatband to Type-III Dirac Cones

by Qingsong Yu, Zhenzhi Liu, Dawei Guo, Shun Liang, Yanpeng Zhang and Zhaoyang Zhang

Nanomaterials 2022, 12(18), 3222; https://doi.org/10.3390/nano12183222 - 16 Sep 2022

Cited by 3 | Viewed by 1416

Abstract

We demonstrate the transition of band structure from flatband to type-III Dirac cones in an electromagnetically induced Kagome photonic lattice generated in a three-level Λ-type ⁸⁵Rb atomic configuration both experimentally and theoretically. Such instantaneously reconfigurable Kagome photonic lattice with flatband is “written” [...] Read more.

We demonstrate the transition of band structure from flatband to type-III Dirac cones in an electromagnetically induced Kagome photonic lattice generated in a three-level Λ-type ⁸⁵Rb atomic configuration both experimentally and theoretically. Such instantaneously reconfigurable Kagome photonic lattice with flatband is “written” by a strong coupling field possessing a Kagome intensity distribution, which can modulate the refractive index of atomic vapors in a spatially periodical manner under electromagnetically induced transparency. By introducing an additional one-dimensional periodic coupling field to cover any one set of the three inequivalent sublattices of the induced Kagome photonic lattice, the dispersion-less energy band can evolve into type-III Dirac cones with linear dispersion by easily manipulating the intensity of the one-dimensional field. Our results may pave a new route to engineer in situ reconfigurable photonic structures with type-III Dirac cones, which can act as promising platforms to explore the underlying physics and beam dynamics. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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16 pages, 10532 KiB

Open AccessArticle

Simplified Limp Frame Model for Application to Nanofiber Nonwovens (Selection of Dominant Biot Parameters)

by Shuichi Sakamoto, Tetsushi Shintani and Tsukasa Hasegawa

Nanomaterials 2022, 12(17), 3050; https://doi.org/10.3390/nano12173050 - 02 Sep 2022

Cited by 4 | Viewed by 1213

Abstract

This study aimed to discover an easy and precise prediction model for the acoustic properties of nanofiber nonwoven fabrics. For this purpose, a prediction model focusing on the two dominant parameters in the Limp frame model—bulk density and flow resistivity—was suggested. The propagation [...] Read more.

This study aimed to discover an easy and precise prediction model for the acoustic properties of nanofiber nonwoven fabrics. For this purpose, a prediction model focusing on the two dominant parameters in the Limp frame model—bulk density and flow resistivity—was suggested. The propagation constant and characteristic impedance was generated from the effective density and effective volume modulus generated by the predictive model and treated as a one-dimensional transfer matrix. The sound absorption coefficient was then estimated using the transfer matrix approach. The trend of the normal Incident sound absorption coefficient measured and the sound absorption coefficient obtained from the predictive model were consistent. Thus, it is suggested that the predictive model for the proposed nanofiber nonwoven composite sheet is valid. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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9 pages, 1443 KiB

Open AccessArticle

SANS Studies of the Gallium–Indium Alloy Structure within Regular Nanopores

by Andrei V. Uskov, Elena V. Charnaya, Aleksandr I. Kuklin, Min Kai Lee, Lieh-Jeng Chang, Yurii A. Kumzerov and Aleksandr V. Fokin

Nanomaterials 2022, 12(13), 2245; https://doi.org/10.3390/nano12132245 - 29 Jun 2022

Cited by 3 | Viewed by 1168

Abstract

Potential applications of nanolattices often require filling their empty space with eutectic metallic alloys. Due to confinement to nanolattices, the structure of phase segregates in eutectic alloys can differ from that in bulk. These problems are poorly understood now. We have used small [...] Read more.

Potential applications of nanolattices often require filling their empty space with eutectic metallic alloys. Due to confinement to nanolattices, the structure of phase segregates in eutectic alloys can differ from that in bulk. These problems are poorly understood now. We have used small angle neutron scattering (SANS) to study the segregation in the Ga-In alloy confined to an opal template with the regular pore network, created by a strict regularity of opal constituents in close similarity with nanolattices. We showed that SANS is a powerful tool to reveal the configuration of segregated phases within nanotemplates. The In-rich segregates were found to have specific structural features as small sizes and ordered arrangement. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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11 pages, 4235 KiB

Open AccessArticle

Design and Analysis of a Hollow Metallic Microlattice Active Cooling System for Microsatellites

by Junming Chen, Longquan Liu, Wenjun Xu, Xiaobin Huang and Haoqiang Sheng

Nanomaterials 2022, 12(9), 1485; https://doi.org/10.3390/nano12091485 - 27 Apr 2022

Viewed by 1609

Abstract

Microsatellites have stringent demands for thermal dissipation systems with high efficiency but low weight, which is a difficult combination to obtain using current technologies. The design method of a new cooling system consisting of hollow metallic microlattice material filled with liquid is developed [...] Read more.

Microsatellites have stringent demands for thermal dissipation systems with high efficiency but low weight, which is a difficult combination to obtain using current technologies. The design method of a new cooling system consisting of hollow metallic microlattice material filled with liquid is developed and proposed, and its heat dissipation performance is analyzed through experimental tests and numerical simulations. Through the analysis results of the influences of the microstructures of the hollow microlattice material, it is found that the effective coefficient (the number of channels taking part in convection) has the highest influence on the heat dissipation performance. Numerical simulation results illustrated that the heating surface temperature can be reduced to 301.7 K through special design, which can meet the heat dissipation requirement of most microsatellites. The new microlattice cooling system in this study improves heat dissipation performance while having very low structural weight, thus providing a feasible substitute for thermal control systems in microsatellites. Full article

(This article belongs to the Special Issue Research on Nano-Lattice)

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